Studies of lactose synthase, the enzyme that regulates lactose production in the mammary gland, will be performed, to elucidate the mechanism of the enzyme, and to determine the molecular basis of its regulation. In particular, the nature of the sites through which the two protein components of the enzyme, galactosyltransferase and alpha-lactalbumin, interact will be determined. Present investigations of the structure of human serum transferrin, the main iron-transport protein of blood, and its mode of action, will be continued.